This invention relates to novel pyrimidine 2'-methylidene nucleosides possessing an excellent antitumor and antiviral activities, their pharmaceutically acceptable salts.
Under the circumstances in which death due to cancer has increased in number, chemotherapy and immunotherapy in addition to surgical therapy have been widely conducted. In this connection, in chemotherapy, cytarabine (cytosine arabinoside), 5-fluorouracil and the like as antimethabolites, which are considered effective against acute leukemia, have been clinically used.
In recent years, the development of preventives and remedies for various viral infections has attracted particular attention with the advance of researches into pathogenic viruses. Antiviral agents for use in chemotherapy heretofore proposed for clinical purposes are idoxuridine, cytarabine, vidarabine, acyclovir and like. (See, for example, Yutaka Mizushima and Teramasa Miyamoto, The Edition of 1986, "Konnichi no Chiryo-yaku (Present-Day Remedies), Kaisetsu to Binran (Explation and Manual)", Nanko-do, pp. 47-50 (Mar. 10, 1986).)
Furthermore, in European Patent Application 0 310 673, there are disclosed novel pyrimidine 2'-alkylidene nucleosides possessing antiviral activities, in Japanese Patent First Publication 1988-258818, anticancer agents comprising 2'-deoxy-2 -methylidenecytidine and its pharmaceutically acceptable salt as active ingredients.
However, the hitherto-known anticancer agents leave much to be desired in respect to therapeutic effect and involve various problems such as side effects. Thus, the development of excellent anticancer agents has been strongly desired from various fields.
Furthermore, most of the above-mentioned antiviral agents have been accompanied by problems including limited clinical applicability, for example, due to antiviral activity spectra, low absorption, poor solubility, easy decomposition, the advent of drug-fast virus strains, and various side effects. Accordingly, there has been an urgent demand for the development of novel antiviral agents.